A proposal to raise California's minimum wage to $15 an hour by 2021 qualified Tuesday to appear on the statewide November ballot.

California's current minimum wage is among the highest in the nation at $10 an hour. The measure backed by a faction of health care workers belonging to the state largest union would raise it by $1 each of the next five years.

Subsequently, minimum wage increases would be tied to the cost of living.

Two groups within the Service Employees International Union have split the organization's support between competing initiatives to raise California's minimum wage.

SEIU United Healthcare Workers West proposed the measure approved Tuesday.

"This is the one that was moving first, this is the one that qualified first, this is the one that's the focus," Sean Wherley, spokesman for the health care workers, said.

The SEIU state council, and the tens of millions of dollars it has promised to spend on a statewide campaign, is behind a different initiative that is still in the signature-gathering process.

That plan would raise wages to $15 by 2020 for large businesses and by 2021 for smaller ones. It would also raise the minimum number of annual paid sick days from three to six.

The SEIU state council has said it hoped the measures could merge, but the qualified measure cannot be amended.

"One or the other would have to be withdrawn," Wherley said.

The union would have until June 30, a state-mandated deadline, to decide whether to remove one of the proposals.

California Lt. Gov. Gavin Newsom is supporting both proposals.

"California has often been the incubator of ideas and policies that spread across the country - this initiative fits that mold and will make our state the leader in the fight against income inequality," Newsom said.

Businesses and Democratic Gov. Jerry Brown have said such a steep wage increase would be incredibly costly.

Oregon officials approved a law earlier this month that will increase that state's minimum wage to nearly $15 in urban areas over the next six years.